The present invention relates to a magnetic tape cassette for use with audio equipment or the like. More particularly, the invention relates to an original compact magnetic tape cassette in which a magnetic tape is wound on flangeless hubs and which has a size not larger than a standard Philips-type audio cassette currently in widespread use.
Various types of conventional magnetic tape cassettes for use with video tape recorder, audio equipment, etc., are known. In common video tape cassettes, the magnetic tape is wound on flanged hubs (reels) in the cassette. On the other hand, in compact magnetic tape cassettes intended for audio use or the like, the magnetic tape is wound on a pair of flangeless hubs. In cassettes having flangeless hubs, it is common practice to provide a friction sheet between each of the upper and lower outer body halves of the cassette and the magnetic tape and hubs to maintain desired rotational properties of the hubs to prevent the tape from being irregularly wound on the hubs.
The recent trend is to reduce the size and weight of cassette tape recorders, and accordingly a need for compact magnetic tape cassettes has arisen. Also, there is always a demand for magnetic tape cassettes capable of recording and reproduction with a high quality and high density.
Digital type recorders and magnetic tapes have recently been introduced to meet these demands. In these recorders, the input analog signal is converted to digital form using pulse code modulation. Also, there has recently become available a large-size video tape cassette intended for digital recording. Such cassettes must be capable of recording signals of a much wider bandwidth than audio cassettes, typically about five times as wide. These video tape cassettes, which are generally intended for use in a rotary-head recorder have an opening provided in their front surface which is closed by a guard panel when the cassette is not in use. Such measures to protect the tape are necessary for such digital-type cassettes due to the extremely high recording density and broad frequency spectrum which must be maintained.
It is possible to apply the same type of construction techniques to a wide bandwidth audio cassette of a more compact size no larger than the size of a standard Philips-type cassette. This type of cassette can be used with a rotary-head type audio cassette recorder. In such an audio cassette it is preferable though to employ flangeless hubs in order to reduce the size and weight of the cassette.
However, such audio cassettes suffer from a significant drawback. Since the cassette is used in a rotary head system, it is necessary to pull the tape out of the cassette for recording and reproduction. To improve the fit of the tape against the rotary head, the tape is slightly displaced in the direction of width of the tape by a guide pin. This displacement can give rise to an excessive force acting in the widthwise direction of the tape. The problem is made more severe due to the fact that the pulled-out length of the tape is small due to the reduced size of the cassette and recorder and the attendant reduced distance between the cassette and the head. This excessive force produces an adverse effect on the winding of the tape on the hubs. That is, the tape has a tendency to be wound irregularly on the hubs.